Timepieces which are modified and adapted to show the local tides and possibly moon conditions have been the subject of development for many years. Patents showing such devices range from Haynes U.S. Pat. No. 2,677,928, filed in 1949, through Bourquin et al. U.S. Pat. No. 4,853,908 issued in 1989. Most of the prior art patents relate to the mechanisms for driving the appropriate indication elements such as dials and pointers as additional elements to the standard timekeeping mechanism. Some of these devices are quite complex and provide a great deal of detailed information. For example, see U.S. Pat. Nos. 3,745,313, 4,623,259 and 4,849,949. A programmable electronic tide clock is shown in U.S. Pat. No. 4,412,749.
U.S. Pat. No. 4,853,908 is of interest and will be considered here in some detail. The moon face and relative tide indicating disc is mounted to the timing mechanism for rotation through one complete day's cycle which Borquin states as occurring every 24 hours and 50 minutes. The position of the moon indicator with respect to a centered position or high tide index enables the user to calculate the next or last high tide time. By viewing the face of the watch the user can count the hours to the next high or low tide. A second rotating disc provides the indication of moon phase in conjunction with tide times. One drawback of this particular watch is that in order to fully set the watch and the moon phase, several minutes and many rotations of the crown are necessary. Another is that tide time is not instantly shown but must be calculated by the user.